The word ‘torpedo’ comes from a Latin word used to describe a species of fish that uses an electric shock to stun its prey. Prior to Roberts Whitehead’s invention it was used to describe all manner of underwater weapons. In 1775 the American inventor David Bushnell used the name for an explosive charge that was the prime weapon system for his revolutionary submarine called ‘Turtle’. The charge, that contained 150lb. of explosive, was to be attached to the bottom of its intended victim with the aid of a large wooden screw and detonated by a clockwork fuse. There were countless inventions like Bushnell’s over the early years of the nineteenth century but today they would better be described under the general name of ‘mine’.

The second device was the ‘tow torpedo’ which is generally known as the ‘Harvey Torpedo’ after the two brothers who invented it, Captain John Harvey RN and Commander Frederick Harvey RN. This torpedo is illustrated below and consists of an explosive charge that was towed from the bow of an attacking vessel. Like the paravane on a minesweeper, objects towed in this fashion will diverge from the towing vessel's course by 45 degrees. The attacking vessel could therefore stand off and deliver the weapon from a range of about 100 to 150 metres. The lever (or horn) mounted on the charge was used to detonate the chemical fuse, depth was regulated by means of the attached floating buoy. The theory was sound, but in practice it was extremely difficult and dangerous to use. Often the tow cable parted, fouled the propeller or the charge would prematurely explode! Despite these imperfections the British Navy purchased the design and were experimenting with it at the time Whitehead was demonstrating his weapon.